Periodic Table and Energy

Question 1

what is periodicity?

Answer 1

repeating pattern of trends across different periods

Question 2

what is the atomic radius trend down a group?

Answer 2

• number of shells increase
• more shielding
• outermost electron further away from nucleus
• nuclear attraction decreases
• radius increases

Question 3

what is the atomic radius trend across a period?

Answer 3

• nuclear charge increases as proton number increase
• nuclear attraction increase
• radius decreases

Question 4

what is first ionisation energy?

Answer 4

energy required to remove one e- from each atom from one mole of a gaseous atom to form one mole of gaseous 1+ ions

Question 5

what is the ionisation trend down a group?

Answer 5

• ionisation energy decreases
• more shells
• more shielding
• weaker nuclear attraction
• less energy needed to remove outer electron

Question 6

what is the ionisation energy trend across a period?

Answer 6

• ionisation energy increases
• more protons
• nuclear charge increases
• radius decreases so nuclear attraction increases
• more energy required to remove an electron

Question 7

what is second ionisation energy?

Answer 7

energy required to remove each e- in turn

Question 8

why do successive ionisation energies increase with ionisation number?

Answer 8

• same proton number
• fewer e- number
• electrons more strongly attracted to nucleus
• more energy needed to remove each e-

Question 9

what can Mg(OH)2 be used for?

Answer 9

antacid
neutralises excess stomach acid

Question 10

what can Ca(OH)2 be used for?

Answer 10

agriculture to neutralise acid soil
reacts with acid substances in the soil

Question 11

what happens to thermal decomposition down group 2?

Answer 11

decrease

Question 12

what colour is Cl2 in water?

Answer 12

pale-green

Question 13

what colour is Cl2 in organic sovent?

Answer 13

pale-green

Question 14

what colour is Br2 in water?

Answer 14

orange

Question 15

what colour is Br2 in organic solvent?

Answer 15

orange

Question 16

what colour is I2 in water?

Answer 16

brown

Question 17

what colour is I2 in organic solvent?

Answer 17

purple

Question 18

how to work out colour of solution?

Answer 18

colour of lone halogen

Question 19

what is an advantage of chlorine?

Answer 19

kills bacteria

Question 20

what is a disadvantage of chlorine?

Answer 20

toxic

Question 21

how to make bleach?

Answer 21

Cl2 (aq) + 2NaOH (aq) -> NaCl (aq) + NaClO (aq) + H2O (l)
cold and dilute sodium hydroxide

Question 22

how to make sodium chlorate (V)?

Answer 22

3Cl2 (aq) + 6NaOH (aq) -> NaClO3 (aq) + 5NaCl (aq) + 3H2O (l)

Question 23

what is the carbonate test?

Answer 23

• add dilute HNO3
• if effervescence seen, carbonate present
  H+ + CO3- -> H2O + CO2

Question 24

what is the sulfate test?

Answer 24

• add HNO3 and Ba(NO3)2
• if white ppt seen, sulfate present
  Ba 2+ + SO4 2- -> BaSO4

Question 25

what is the halide test?

Answer 25

- add AgNO3 - if white ppt seen, chlorine present Ag+ + Cl- -> AgCl - if cream ppt seen, bromine present Ag+ + Br- -> AgBr - if yellow ppt seen, iodine present Ag+ + I- -> Agl

Question 26

what happens when concentrated NO3 added to silver halide?

Answer 26

- dissolves Cl- - dissolves Br- - doesnt dissolve I-

Question 27

what happens when dilute NO3 added to silver halide?

Answer 27

- dissolves CL- - doesnt dissolve Br- - doesnt dissolve I-

Question 28

what is the rate of a reaction?

Answer 28

change in conc of a reactant/product per unit time

Question 29

what is a catalyst?

Answer 29

lowers activation energy by providing an alternate pathway and increases ror

Question 30

what happens to ror with conc?

Answer 30

- as conc increases - ror increases - more molecules in given volume - more frequent successful collisions

Question 31

what happens to ror with pressure?

Answer 31

- as pressure increases - ror increases - number of molecules in volume increases - more frequent successful collisions

Question 32

what happens to ror with temp?

Answer 32

- as temp increases - ror increases - molecules have more kinetic energy - more frequent successful collisions

Question 33

what is activation energy?

Answer 33

minimum energy required to start a reaction by breaking bonds in the reactants

Question 34

what are the benefits of using a catalyst?

Answer 34

- reduces CO2 emissions - less cost due to lower energy demand - higher % yield of desired product

Question 35

what is the Haber process?

Answer 35

N2 (g) + H2 (g) -> 2NH3 (g)

Question 36

how to work out ror from a graph?

Answer 36

draw tangent and work out gradient

Question 37

what is a reversible reaction?

Answer 37

rate of forward reaction = rate of backwards reaction

Question 38

what is dynamic equilibrium?

Answer 38

when the rate of forward reaction equals rate of backward reaction in a closed system

Question 39

what are the characteristics of dynamic equilibrium?

Answer 39

temp, pressure, conc of reactants and products dont change

Question 40

how to know when a reaction reaches equilibrium?

Answer 40

colour remains constant conc remains constant

Question 41

how does catalyst affect equilibrium?

Answer 41

doesnt affect

Question 42

how does temp affect equilibrium?

Answer 42

higher temp -> moves to right (endo)/ left (exo) lower temp -> moves to right (exo)/ left (endo)

Question 43

how does conc affect equilibrium?

Answer 43

moves to the opposite side of which conc has increased

Question 44

how does pressure affect equilibrium?

Answer 44

higher pressure -> side with less moles

Question 45

how to write expression of equilibrium constant?

Answer 45

products over reactants balancing numbers are powers

Question 46

what does equilibrium constant depend on?

Answer 46

temp increase -> right decrease -> left

Question 47

what happens when Kc < 1?

Answer 47

equilibrium shifts to left

Question 48

what happens when Kc > 1?

Answer 48

equilibrium shifts to right

Question 49

what are the standard conditions?

Answer 49

temp - 25 degrees C pressure - 1 atm conc - 1moldm-3

Question 50

what is the enthalpy change of neutralisation?

Answer 50

enthalpy change to form one mole of H2O from neutralisation under standard conditions

Question 51

what is enthalpy change of formation?

Answer 51

enthalpy change of the formation of one mole of a compound from its elements under standard conditions

Question 52

what is enthalpy change of combustion?

Answer 52

enthalpy change for one mole of a substance to undergo complete combustion under standard conditions

Question 53

how to know when a reaction is endothermic?

Answer 53

enthalpy change is positive

Question 54

how to know when a reaction is exothermic?

Answer 54

enthalpy change is negative

Question 55

how to work our EC of combustion?

Answer 55

CRaP

Question 56

how to work out EC of formation?

Answer 56

FliPpeR

Question 57

what direction do the arrows face for formation?

Answer 57

upwards

Question 58

what direction do the arrows face for combustion?

Answer 58

downwards

Question 59

how to work out enthalpy change?

Answer 59

break take make

Question 60

how to work out enthalpy change from an experiment?

Answer 60

- Q=mcT - mol = mass/Mr - divide both

Question 61

how to know an experiment is exothermic?

Answer 61

temp increases

Question 62

how to know an experiment is endothermic?

Answer 62

temp decreases

Question 63

why might calculated enthalpy change be different to standard?

Answer 63

- not standard conditions - heat loss/gain

Question 64

what happens to pH down group 2?

Answer 64

increases